Enhancing the performance of air conditioning systems by integrating phase change materials: A comprehensive review

Energy conservation is an important aspect of the modern industry. The need for heating, ventilation, and air conditioning (HVAC) systems is on the rise due to global warming, population growth, and the need for good air quality to prevent airborne illnesses like COVID-19. Since air conditioning (AC) systems use a significant amount of energy, it's crucial to try to lower the energy consumed by these systems. There are many ways to reduce the energy consumed by AC systems, but using phase change materials (PCMs) is a simple and convenient way to achieve that purpose. In this paper, a comprehensive review of different AC systems that integrate PCMs is presented. The AC systems were divided into active AC systems, free cooling AC systems, PCM as thermal energy storage (TES) for cold air applications, and heating systems. This review presents the results of the enhancements that the PCM added to these systems in terms of lowering power consumption and an increasing efficiency. The review paper discusses the different methods that the researchers used to enhance the properties of the PCMs and an increase their thermal conductivity, as well as the aspects that affect the PCM performance as a TES, such as the type of PCM, the encapsulation type, the geometry of the TES, and the phase change temperature that should be selected according to the application. Significant results were achieved by integrating PCM with AC systems: a reduction in electrical power of 13.84 % in winter and 16.13 % in summer was achieved in split unit AC, an electricity consumption reduction reaching up to 73 % in a free cooling system, a notable 30 % reduction in CO2 emissions in a PCM as TES application, and the integration of PCM with heating systems can reduce the adverse impacts of weather volatility and maximize the use of solar energy. •Use of PCM can improve the energy efficiency of air-conditioning systems.•Thermal Storage has capabilities in in peak load shifting and demand-side management.•Integrated PCM with AC system has environmental impact in terms of potential reduction in greenhouse gas emissions.•System Performance improved in terms of cooling performance and indoor thermal comfort.•Issues such as PCM encapsulation, integration methods, and system design are addressed